Israel faced the prospect of escalation on two fronts Thursday as the repercussions of the kidnapping and slaying of three Israeli teens in the West Bank threatened to ignite a broader conflagration.

Israeli forces were bolstered around the Gaza Strip to confront rocket volleys from the territory. In East Jerusalem, Palestinian street protests triggered by the apparent revenge killing of an Arab youth flared anew.

The military buildup around Gaza came after three weeks of simmering cross-border tensions stoked by the abduction and killing of the Jewish teenagers.

An Israeli crackdown in the West Bank on the militant Islamist group Hamas, which Israel blamed for the kidnapping and slayings of the three Jewish teenagers, has been accompanied by a stepped-up cycle of rocket salvos and Israeli airstrikes in Gaza.

While both Hamas and Israel have signaled they do not seek an escalation, commentators warned that the situation could spin out of control.

The reinforcement of infantry, armor and artillery units near the Gaza Strip was defensive and did not signal an imminent military campaign, said Lt. Col. Peter Lerner, an Israeli army spokesman.

“We are not going on some sort of offensive,” Lerner said. “We are trying to send a message to Hamas: Take control and stop the launching of rockets at Israel.”

Prime Minister Benjamin Netanyahu said Israel was preparing for two possibilities: Either the rocket firing will stop and military operations will be suspended, or rocket attacks will continue and beefed-up Israeli troops will “act forcefully.”

Israel and Hamas agreed to a cease-fire in Gaza after an eight-day Israeli offensive against the group in 2012. Most of the rocket firing has been attributed to radical factions defying Hamas, which controls the coastal enclave and has sought to rein in the attacks.

But Lerner said that the longer range of some of the most recent rocket strikes indicated that Hamas had been “directly involved.”

“We are hoping that in the next few hours Hamas will realize that it is not in their best interest to continue to launch rockets at us,” Lerner said.

Rockets hit two houses in the southern Israeli town of Sderot on Thursday, causing damage but no casualties after residents took shelter in response to alarms.

Israeli airstrikes overnight hit 15 Hamas targets in the Gaza Strip, including concealed rocket launchers, weapon storage facilities and “terror activity sites,” an army statement said. Palestinians said the airstrikes hit training bases of Hamas and Islamic Jihad, a group that has often defied the cease-fire.

The Health Ministry in Gaza said that 10 civilians were injured, including a pregnant woman who was seriously wounded. Palestinians said that the bases targeted had been evacuated in expectation of the Israeli strikes.

The armed wing of Hamas warned Israel against a broader military operation in Gaza, threatening that it would respond with long-range rocket strikes. “We are ready for all options,” a spokesman said.

Tensions remained high in East Jerusalem, where street clashes flared for the second consecutive day. The unrest erupted on Wednesday after a Palestinian teenager was abducted and killed in an apparent revenge attack for the slaying of the three Israeli teens in the West Bank.

As the body of 16-year-old Muhammad Abu Khdeir was held by Israeli authorities for an autopsy, youths again took to the streets of his East Jerusalem neighborhood to throw stones at police and barricade roads with trash bins. Riot officers responded with tear-gas and stun grenades, according to reports from the scene.

In daylong clashes on Wednesday, rioters burned tires and hurled stones and Molotov cocktails at police, smashing stations of an Israeli-run light rail line that runs through the neighborhood.

On Thursday, one of the wrecked stations carried Hebrew graffiti that said: “Death to Israel. Death to Jews.”

Israel, meanwhile, has been swept by an anti-Arab backlash since the slaying of the three Jewish teenagers – Eyal Yifrah, 19, Naftali Fraenkel, 16 and Gil-Ad Shaer, 16 – whose bodies were found in a West Bank field on Monday, 18 days after they were seized.

A Facebook page titled “The people of Israel demand revenge” garnered 35,000 fans, with soldiers and civilians posting pictures of themselves holding up makeshift signs calling for vengeance. Two smiling young women held up a sign that said: “Hating Arabs is not racism, it’s values!”

Alarmed by the surge of hate speech, the Israeli attorney general has ordered the police to investigate cases of incitement to violence on social media, and the Justice Ministry published a toll-free number for reporting cases of incitement and racist speech.

The army said that four soldiers in a unit of ultra-Orthodox Jews had been jailed for a posting that violated military rules. Israel Radio said they had posted an image of themselves with the words: “Bibi, let us eliminate the terrorists.” Bibi is the nickname of Prime Minister Netanyahu.

Bucking the trend, the family of Fraenkel, one of the slain Israeli teens, issued a statement condemning the killing of the Palestinian youth.

“If indeed an Arab youngster was murdered for nationalist reasons, then it is a horrifying and shocking deed,” the statement said. “There is no difference between blood and blood. Murder is murder, whatever the age and nationality. There is no justification, no forgiveness and no atonement for any murder.”